This study is to assess the efficacy and safety of the glucagon receptor antagonist BAY 27-9955 when used in conjunction with insulin; in patients with suboptimally controlled type 2 diabetes. The study will be a randomized, double blind, placebo controlled, multicenter, crossover study in patients with type 2 diabetes who are without serious medical conditions and who are being concomitantly treated with diet and insulin. The overall design of the study is as follows: a two week screening period, a 21-day treatment period, a 14-day washout period, and then a crossover to the alternative treatment for 21 days.